I experience this problem too with CS5 (5.03) on a decent i750 win7 64bit workstation, with 12 GB ram and 3 disk setup (C: SSD drive with software, D: 7200 rpm for preview, cache, E: Media and project).
It’s very annoying, only switching between premiere and internet browser or file browser. Going back to premiere and it freezes for 5-10 seconds.
In the premiere settings I’ve assigned the max amount of ram for premiere, 9 gb.
I’ve experienced this on other PCs aswell. This is so annoying, slowing down editing alot!
Very greatful for any advice!